Friction and wear reduction using liquid crystal base stocks

ABSTRACT

wherein A is a mono-ring or a multi-ring aromatic group, R1 is the same or different and is a substituted or unsubstituted, hydrocarbon, alkoxy, or alkylthio group having from 2 to 24 carbon atoms, and n is a value from 1 to 12. The lubricating oil base stock has a kinematic viscosity of 2 cSt to 200 cSt at 40° C., as determined according to ASTM D445, and a kinematic viscosity of 1 cSt to 25 cSt at 100° C., as determined according to ASTM D445.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/611,081, filed on Dec. 28, 2017, the entire contents of which areincorporated herein by reference.

In addition, this application also claims the benefit of related U.S.Provisional Application Nos. 62/611,057 and 62/611,072, both filed onDec. 28, 2017, the entire contents of which are also incorporated hereinby reference.

FIELD

This disclosure relates to liquid crystal base stocks, in particular,liquid crystal base stocks, useful as machining and pre-run (run-in)fluids that enable achievement of low wear and friction values. Also,this disclosure relates to method for improving friction and wearcontrol, while maintaining or improving energy efficiency, in an engineor other mechanical component lubricated with a lubricating oil, byusing a lubricating oil containing at least one lubricating oil basestock having one or more liquid crystals.

BACKGROUND

The use of surface active lubricant additives to form protectivetribofilms is ubiquitous. However, many of these surface films have highroughness and therefore friction values may not be optimized resultingin loss of energy efficiency and the potential for surface fatigue overtime.

Metal parts that come in contact with each other meet at theirasperities resulting in high localized pressures and temperatures, highfriction, and adhesive wear. On rough surfaces, surface fatigue maycause pitting/spalling over time.

To address the challenge of improving energy efficiency and uptimethrough friction and wear reduction, lubricant formulators use surfaceactive additives in traditional lubricants, and/or lower the oilviscosity to reduce churning losses. While these approaches yieldincremental improvements, they less and less frequently result in largeefficiency gains.

New ways to arrive at energy efficiency in lubricated applications arehighly sought after to reduce energy dependence and carbon dioxideoutput while increasing the ratio of energy used to energy wasted. Thereis a further need to improve uptime:downtime ratios through extension ofequipment life.

A major challenge in lubricant formulation is the development ofalternate pathways to improving energy efficiency and uptime throughfriction and wear reduction.

SUMMARY

In accordance with this disclosure, fluids, such as liquid crystal baseoils are provided as machining or run-in fluids that enable achievementof ultralow friction values.

Also in accordance with this disclosure, liquid crystal base stocks areprovided, in particular, liquid crystal base stocks, useful as machiningand pre-run fluids that enable achievement of low wear and frictionvalues. Also, this disclosure provides a method for improving frictionand wear control, while maintaining or improving energy efficiency, inan engine or other mechanical component lubricated with a lubricatingoil, by using a lubricating oil containing at least one lubricating oilbase stock having one or more liquid crystals.

This disclosure relates in part to a lubricating oil base stockcomprising one or more liquid crystals. The one or more liquid crystalsare represented by the formula:

A—(R1)_(n)

wherein A is a mono-ring or a multi-ring aromatic group, R1 is the sameor different and is a substituted or unsubstituted, hydrocarbon, alkoxy,or alkylthio group having from about 2 to about 24 carbon atoms, and nis a value from about 1 to about 12. The lubricating oil base stock hasa kinematic viscosity of about 2 cSt to about 200 cSt at 40° C., asdetermined according to ASTM D445, and a kinematic viscosity of about 1cSt to about 25 cSt at 100° C., as determined according to ASTM D445.

This disclosure also relates in part to a method for improving frictionand wear control, while maintaining or improving energy efficiency, inan engine or other mechanical component lubricated with a lubricatingoil, by using as the lubricating oil a formulated oil. The formulatedoil has a composition comprising at least one lubricating oil basestock. The at least one lubricating oil base stock comprises one or moreliquid crystals, wherein the one or more liquid crystals are representedby the formula:

A—(R1)_(n)

wherein A is a mono-ring or a multi-ring aromatic group, R1 is the sameor different and is a substituted or unsubstituted, hydrocarbon, alkoxyor alkylthio group having from about 2 to about 24 carbon atoms, and nis a value from about 1 to about 12. The lubricating oil base stock hasa kinematic viscosity of about 2 cSt to about 200 cSt at 40° C., asdetermined according to ASTM D445, and a kinematic viscosity of about 1cSt to about 25 cSt at 100° C., as determined according to ASTM D445.Friction and wear control are improved and energy efficiency ismaintained or improved as compared to friction control, wear control andenergy efficiency achieved using a lubricating oil containing alubricating oil base stock other than the lubricating oil base stockcomprising one or more liquid crystals.

This disclosure further relates in part to a method for improving andmaintaining friction and wear control in an engine or other mechanicalcomponent lubricated with a lubricating oil. The method comprises: (i)providing an engine or other mechanical component having mated metalsurfaces; (ii) conducting a run-in by contacting the mated metalsurfaces with a first lubricating oil having a composition comprising atleast one lubricating oil base stock; wherein the at least onelubricating oil base stock comprises one or more liquid crystals,wherein the one or more liquid crystals are represented by the formula:

A—(R1)_(n)

wherein A is a mono-ring or a multi-ring aromatic group, R1 is the sameor different and is a substituted or unsubstituted, hydrocarbon, alkoxyor alkylthio group having from about 2 to about 24 carbon atoms, and nis a value from about 1 to about 12; and wherein the lubricating oilbase stock has a kinematic viscosity of about 2 cSt to about 200 cSt at40° C., as determined according to ASTM D445, and a kinematic viscosityof about 1 cSt to about 25 cSt at 100° C., as determined according toASTM D445; wherein friction and wear control are improved as compared tofriction control and wear control achieved using a lubricating oilcontaining a lubricating oil base stock other than the lubricating oilbase stock comprising one or more liquid crystals; (iv) removing thefirst lubricating oil from the engine or other mechanical componentafter the run-in; and (v) contacting the mated metal surfaces with asecond lubricating oil containing a lubricating oil base stock otherthan the lubricating oil base stock comprising one or more liquidcrystals; wherein the improved friction control and wear control fromconducting the run-in are maintained.

It has been surprisingly found that, in accordance with this disclosure,improvements in wear control in an engine or other mechanical componentlubricated with a lubricating oil are obtained, when the lubricating oilcontains at least one lubricating oil base stock comprised of one ormore liquid crystals.

In particular, it has been surprisingly found that, in accordance withthis disclosure, with respect to the lubricating oil base stockcomprised of one or more liquid crystals, in friction coefficientmeasurements of the lubricating oil base stock by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than about 0.25, or less than about 0.20,or less than about 0.10.

Also, in particular, it has been surprisingly found that, in accordancewith this disclosure, the liquid crystal base oils can be used as run-influids to reduce surface roughness, pattern a surface, resulting inevenly distributed load, lower contact pressures and reduced friction,in a built machine, improving friction and wear tendency even afterbeing exchanged for a more traditional lubricant.

Other objects and advantages of the present disclosure will becomeapparent from the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 graphically depicts, for liquid crystal hexakis(octylthio)benzene(D1), an unprecedented friction drop over time on the SRVcylinder-on-disk line contact under 50N load, 50 Hz reciprocation, 1mmstroke length, a temperature of 50° C., and the cylinder positioned 5°off the axis of reciprocation, in accordance with the Examples.

FIG. 2 graphically depicts the effect of test conditions on the frictionperformance of the liquid crystal D1. It surprisingly shows thatincreasing temperature at the same load increases friction, whileincreasing load at the same temperature reduces friction, in accordancewith the Examples

FIG. 3 shows interferometry images for worn SRV disk post-testing at 50Hz, 50° C., 1 mm stroke, 8 hours for fluid PAO3.6 (left, a), and forliquid crystal fluid D1 (right, b), in accordance with the Examples.

FIG. 4 shows the similarity of friction performance profile of anotherinventive molecule, dihexyl bi-thiophene relative to liquid crystal D1by opposition to the performance of 8 cSt PAO, which frictioncoefficient remains unchanged and higher for the whole test duration onSRV line contact at 50N, 50° C., 50 Hz, 1.0 mm, in accordance with theExamples

FIG. 5 is a graphical representation of the relationship between thefinal equilibrium coefficient of friction and the SRV line contact testapplied temperature and load, in accordance with the Examples

FIG. 6 is a graphical representation of the relationship between thefinal equilibrium coefficient of friction and the SRV line contact testapplied load, in accordance with the Examples

FIG. 7 shows Table containing coefficient of friction at specific timeinterval for liquid crystal D1, 8 cSt PAO and their mixtures, inaccordance with the Examples

FIG. 8 is a graphical representation of coefficient of friction atspecific time interval for liquid crystal D1, 8 cSt PAO and theirmixtures. It clearly shows the advantage of adding liquid crystal D1even at concentrations as low as 10%, in accordance with the Examples

FIG. 9 shows results for friction versus test duration on SRV linecontact at 50N, 50° C., 50 Hz, 1.0 mm, with two 8 hour time intervals onthe same sample specimen: hours 1-8 D1 liquid crystal; hours 9-16 PAO 8in accordance with the Examples.

FIG. 10 is a list of coefficient of friction measured after 20 hours SRVruns at specific load and temperature in accordance with the Examples.

DETAILED DESCRIPTION Definitions

“About” or “approximately.” All numerical values within the detaileddescription and the claims herein are modified by “about” or“approximately” the indicated value, and take into account experimentalerror and variations that would be expected by a person having ordinaryskill in the art.

“Liquid crystal” fluids mean highly anisotropic fluids that existbetween the boundaries of the solid and conventional isotropic liquidphase. The phase is a result of long-range orientational ordering amongconstituent molecules that occurs within certain ranges or temperaturein melts and solutions of many organic compounds. The various liquidcrystal phases may be characterized by the type of ordering. Among theseare namely nematic, smectic or discotic phases.

“Smectic liquid crystals” refer to hydrocarbon molecules that arearranged in layers, with the long molecular axes approximatelyperpendicular to the laminar planes. The only long range order extendsalong this axis, with the result that individual layers can slip overeach other (soap-like in nature). A smectic phase of a liquid crystalcan possess two directions of order including one along the axis ofmolecular orientation, and the other along the traverse axis wheremolecules show layering.

“Major amount” as it relates to components included within thelubricating oils of the specification and the claims means greater thanor equal to 50 wt. %, or greater than or equal to 60 wt. %, or greaterthan or equal to 70 wt. %, or greater than or equal to 80 wt. %, orgreater than or equal to 90 wt. % based on the total weight of thelubricating oil.

“Minor amount” as it relates to components included within thelubricating oils of the specification and the claims means less than 50wt. %, or less than or equal to 40 wt. %, or less than or equal to 30wt. %, or greater than or equal to 20 wt. %, or less than or equal to 10wt. %, or less than or equal to 5 wt. %, or less than or equal to 2 wt.%, or less than or equal to 1 wt. %, based on the total weight of thelubricating oil.

“Essentially free” as it relates to components included within thelubricating oils of the specification and the claims means that theparticular component is at 0 weight % within the lubricating oil, oralternatively is at impurity type levels within the lubricating oil(less than 100 ppm, or less than 20 ppm, or less than 10 ppm, or lessthan 1 ppm).

“Flat viscosity” temperature performance as it relates to the lubricantbase stocks and lubricating oils disclosed herein mean that theviscosity does not vary as a function of temperature over a temperaturerange from 20 to 100 deg. C.

“Other lubricating oil additives” as used in the specification and theclaims means other lubricating oil additives that are not specificallyrecited in the particular section of the specification or the claims.For example, other lubricating oil additives may include, but are notlimited to, antioxidants, detergents, dispersants, antiwear additives,corrosion inhibitors, viscosity modifiers, metal passivators, pour pointdepressants, seal compatibility agents, antifoam agents, extremepressure agents, friction modifiers and combinations thereof.

“Other mechanical component” as used in the specification and the claimsmeans an electric vehicle component, a hybrid vehicle component, a powertrain, a driveline, a transmission, a gear, a gear train, a gear set, acompressor, a pump, a hydraulic system, a bearing, a bushing, a turbine,a piston, a piston ring, a cylinder liner, a cylinder, a cam, a tappet,a lifter, a gear, a valve, or a bearing including a journal, a roller, atapered, a needle, and a ball bearing.

“Hydrocarbon” refers to a compound consisting of carbon atoms andhydrogen atoms.

“Alkane” refers to a hydrocarbon that is completely saturated. An alkanecan be linear, branched, cyclic, or substituted cyclic.

“Olefin” refers to a non-aromatic hydrocarbon comprising one or morecarbon-carbon double bond in the molecular structure thereof.

“Mono-olefin” refers to an olefin comprising a single carbon-carbondouble bond.

“Cn” group or compound refers to a group or a compound comprising carbonatoms at total number thereof of n. Thus, “Cm-Cn” group or compoundrefers to a group or compound comprising carbon atoms at a total numberthereof in the range from m to n. Thus, a C₁-C₅₀ alkyl group refers toan alkyl group comprising carbon atoms at a total number thereof in therange from 1 to 50.

“Carbon backbone” refers to the longest straight carbon chain in themolecule of the compound or the group in question. “Branch” refer to anysubstituted or unsubstituted hydrocarbyl group connected to the carbonbackbone. A carbon atom on the carbon backbone connected to a branch iscalled a “branched carbon.”

“SAE” refers to SAE International, formerly known as Society ofAutomotive Engineers, which is a professional organization that setsstandards for internal combustion engine lubricating oils.

“SAE J300” refers to the viscosity grade classification system of enginelubricating oils established by SAE, which defines the limits of theclassifications in rheological terms only.

“Base stock” or “base oil” interchangeably refers to an oil that can beused as a component of lubricating oils, heat transfer oils, hydraulicoils, grease products, and the like.

“Lubricating oil” or “lubricant” interchangeably refers to a substancethat can be introduced between two or more surfaces to reduce the levelof friction between two adjacent surfaces moving relative to each other.A lubricant base stock is a material, typically a fluid at variouslevels of viscosity at the operating temperature of the lubricant, usedto formulate a lubricant by admixing with other components. Non-limitingexamples of base stocks suitable in lubricants include API Group I,Group II, Group III, Group IV, and Group V base stocks. PAOs,particularly hydrogenated PAOs, have recently found wide use inlubricants as a Group IV base stock, and are particularly preferred. Ifone base stock is designated as a primary base stock in the lubricant,additional base stocks may be called a co-base stock.

All kinematic viscosity values in this disclosure are as determinedpursuant to ASTM D445. Kinematic viscosity at 100° C. is reported hereinas KV100, and kinematic viscosity at 40° C. is reported herein as KV40.Unit of all KV100 and KV40 values herein is cSt unless otherwisespecified.

All viscosity index (“VI”) values in this disclosure are as determinedpursuant to ASTM D2270.

All Noack volatility (“NV”) values in this disclosure are as determinedpursuant to ASTM D5800 unless specified otherwise. Unit of all NV valuesis wt%, unless otherwise specified.

All pour point values in this disclosure are as determined pursuant toASTM D5950 or D97.

All CCS viscosity (“CCSV”) values in this disclosure are as determinedpursuant to ASTM 5293. Unit of all CCSV values herein is millipascalsecond (mPa·s), which is equivalent to centipoise), unless specifiedotherwise. All CCSV values are measured at a temperature of interest tothe lubricating oil formulation or oil composition in question. Thus,for the purpose of designing and fabricating engine oil formulations,the temperature of interest is the temperature at which the SAE J300imposes a minimal CCSV.

All percentages in describing chemical compositions herein are by weightunless specified otherwise. “Wt. %” means percent by weight.

Liquid Crystal Base Stocks, Lubricating Oils & Methods for ImprovingFriction and Wear Control

In accordance with this disclosure, liquid crystal base oils areprovided as machining or run-in fluids that enable achievement ofultralow friction values.

This disclosure relates to the use of liquid crystal fluids to smoothand conform mated metal surfaces by using the fluids as lubricants andrunning the fluid under load. The resulting paired surfaces are of lowroughness and appear brushed in nature, resulting in ultralow frictionbetween parts even when the parts are flooded with low viscosity baseoil.

The liquid crystal base oils can be used as run-in fluids to reducesurface roughness, pattern a surface, resulting in evenly distributedload, lower contact pressures and reduced friction. The use of liquidcrystal base oils has been shown to smooth and mate surfaces, resultingin decreased friction and wear once surfaces are mated. The liquidcrystal base oils may be removed after achievement of run-in, andtraditional lubricants used to maintain the ultralow friction values.

The liquid crystal base oils may also be used in the machining of partsto achieve low roughness and the pattern of a brushed surface. Theliquid crystal base oils used in machining to provide highly finishedsurfaces that will have improved friction and wear in application wouldgreatly improve energy efficiency. The liquid crystal base oils can alsobe used as a fluid to run-in a built machine, improving friction andwear tendency even after being exchanged for a more traditionallubricant.

Also, for the lubricants containing liquid crystal base stocks of thisdisclosure, it has been found that, in friction coefficient measurementsof the lubricating oil base stock by a reciprocating cylinder-on-disc(RCD) Schwingung (oscillating), Reibung (friction), Verschleiž (wear)test machine (SRV) in accordance with ASTM D5707, the frictioncoefficient is less than about 0.25.

Further, for the lubricants containing liquid crystal base stocks ofthis disclosure, it has been found that, in friction coefficientmeasurements of the lubricating oil base stock by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than about 0.20.

Yet further, for the lubricants containing liquid crystal base stocks ofthis disclosure, it has been found that, in friction coefficientmeasurements of the lubricating oil base stock by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear)test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than about 0.10.

In an embodiment, the lubricants containing liquid crystal base oils ofthis disclosure, can be blended with one or more additives, e.g., aviscosity modifier (e.g., a polymer thickening agent), to form bimodalblends.

The present disclosure provides lubricant compositions with excellentantiwear properties. Antiwear additives are generally required forreducing wear in operating equipment where two solid surfaces engage incontact. In the absence of antiwear chemistry, the surfaces can rubtogether causing material loss on one or both surfaces which caneventually lead to equipment malfunction and failure. Antiwear additivescan produce a protective surface layer which reduces wear and materialloss. Most commonly the materials of interest are metals such as steeland other iron-containing alloys. However, other materials such asceramics, polymer coatings, diamond-like carbon, correspondingcomposites, and the like can also be used to produce durable surfaces inmodern equipment. The lubricant compositions of this disclosure canprovide antiwear properties to such surfaces.

The lubricant compositions of this disclosure provide advantaged wear,including advantaged wear and friction, performance in the lubricationof internal combustion engines, power trains, drivelines, transmissions,gears, gear trains, valve trains, gear sets, and the like.

Also, the lubricant compositions of this disclosure provide advantagedwear, including advantaged wear and friction, performance in thelubrication of mechanical components, which can include, for example,pistons, piston rings, cylinder liners, cylinders, cams, tappets,lifters, bearings (journal, roller, tapered, needle, ball, and thelike), gears, valves, and the like.

Further, the lubricant compositions of this disclosure provideadvantaged wear, including advantaged wear and friction, performance asa component in lubricant compositions, which can include, for example,lubricating liquids, semi-solids, solids, greases, dispersions,suspensions, material concentrates, additive concentrates, and the like.

Also, the lubricant compositions of this disclosure provide advantagedwear, including advantaged wear and friction, performance inspark-ignition internal combustion engines, compression-ignitioninternal combustion engines, mixed-ignition (spark-assisted andcompression) internal combustion engines, and the like, through thegeneration of tribofilms under loading/temperature conditions relevantto light-duty passenger vehicle operation.

Further, the lubricant compositions of this disclosure provideadvantaged wear, including advantaged wear and friction, performancethrough the generation of tribofilms on lubricated surfaces thatinclude, for example, the following: metals, metal alloys, non-metals,non-metal alloys, mixed carbon-metal composites and alloys, mixedcarbon-nonmetal composites and alloys, ferrous metals, ferrouscomposites and alloys, non-ferrous metals, non-ferrous composites andalloys, titanium, titanium composites and alloys, aluminum, aluminumcomposites and alloys, magnesium, magnesium composites and alloys,ion-implanted metals and alloys, plasma modified surfaces; surfacemodified materials; coatings; mono-layer, multi-layer, and gradientlayered coatings; honed surfaces; polished surfaces; etched surfaces;textured surfaces; mircro and nano structures on textured surfaces;super-finished surfaces; diamond-like carbon (DLC), DLC withhigh-hydrogen content, DLC with moderate hydrogen content, DLC withlow-hydrogen content, DLC with near-zero hydrogen content, DLCcomposites, DLC-metal compositions and composites, DLC-nonmetalcompositions and composites; ceramics, ceramic oxides, ceramic nitrides,FeN, CrN, ceramic carbides, mixed ceramic compositions, and the like;polymers, thermoplastic polymers, engineered polymers, polymer blends,polymer alloys, polymer composites; materials compositions andcomposites containing dry lubricants, that include, for example,graphite, carbon, molybdenum, molybdenum disulfide,polytetrafluoroethylene, polyperfluoropropylene,polyperfluoroalkylethers, and the like.

Lubricating Oil Base Stocks Containing Liquid Crystals

The lubricating oil base stocks of this disclosure comprise one or moreliquid crystals. The one or more liquid crystals are represented by theformula:

A—(R1)_(n)

wherein A is an aromatic group, R1 is the same or different and is asubstituted or unsubstituted, hydrocarbon, alkoxy or alkylthio grouphaving from about 2 to about 24 carbon atoms, and n is a value fromabout 1 to about 12. The lubricating oil base stock has a kinematicviscosity of about 2 cSt to about 200 cSt at 40° C., as determinedaccording to ASTM D445, and a kinematic viscosity of about 1 cSt toabout 25 cSt at 100° C., as determined according to ASTM D445.

Illustrative liquid crystals useful in this disclosure include, forexample, those represented by the formulae:

In particular, illustrative liquid crystals useful in this disclosureinclude, for example, hexakis(octylthio)benzene, and mixtures thereof.

The liquid crystal materials of this disclosure access a state of matterthat is both fluid and anisotropic in nature—essentially these materialsare not solids, which possess a highly ordered crystalline structure andlack ability of translation of molecules in any direction, and they arenot liquids, which are characterized by their lack of order butintermolecular forces that overcome kinetic energy, keeping them in acondensed phase. Instead liquid crystals can be considered “partlyordered” in that in some direction(s) they may appear ordered, and inothers they may appear disordered. These materials are thereforeanisotropic in nature, and the amount of ordering seen depends on fromwhich angle they are viewed. A discotic phase of a liquid crystalincludes disc-shaped crystals in columnar phases. Their molecules have asymmetric branched formula which can be approximated by a flat disc.Discotics demonstrate the layered arrangement like smectic crystals.Their molecules lie in the layer planes forming close hexagonal packing.

Accordingly, as used herein, “liquid crystal” means highly anisotropicfluids that exist between the boundaries of the solid and conventionalisotropic liquid phase. The phase is a result of long-rangeorientational ordering among constituent molecules that occurs withincertain ranges or temperature in melts and solutions of many organiccompounds.

As used herein, “discotic liquid crystals” refers to hydrocarbonmolecules that are arranged in layers. Discotic phase liquid crystalsinclude disc-shaped crystals in columnar phases. Their molecules have asymmetric branched formula which can be approximated by a flat disc.Discotic crystals demonstrate the layered arrangement like smecticcrystals. Their molecules lie in the layer planes forming closehexagonal packing.

The liquid crystal base oils of this disclosure conveniently have akinematic viscosity, according to ASTM standards, of about 2 cSt toabout 200 cSt (or mm² /s) at 40° C. and preferably of about 2.5 cSt toabout 100 cSt (or mm² /s) at 40° C., often more preferably from about2.5 cSt to about 50 cSt at 40° C. Also, the liquid crystal base oilconveniently has a kinematic viscosity, according to ASTM standards, ofabout 1 cSt to about 25 cSt (or mm²/s) at 100° C. and preferably ofabout 2.5 cSt to about 20 cSt (or mm²/s) at 100° C., often morepreferably from about 2.5 cSt to about 15 cSt at 100° C.

Mixtures of liquid crystal base oils may be used if desired. Bi-modal,tri-modal, and additional combinations of mixtures of liquid crystalbase oils and optional Group I, II, III, IV, and/or V base stocks may beused if desired. With mixtures of liquid crystal base oils and Group I,II, III, IV, and/or V base stocks, the liquid crystal base oil ispresent is an amount ranging from about 5 to about 99 weight percent orfrom about 10 to about 95 weight percent, preferably from about 20 toabout 99 weight percent or from about 40 to about 95 weight percent, andmore preferably from about 50 to about 99 weight percent, based on thetotal weight of the composition. Preferably, with mixtures of liquidcrystal base oils and Group I, II, III, IV, and/or V base stocks, theliquid crystal base oil is present is an amount ranging from about 25 toabout 99 weight percent or from about 25 to about 95 weight percent,preferably from about 40 to about 99 weight percent or from about 50 toabout 95 weight percent, and more preferably from about 55 to about 95weight percent, based on the total weight of the composition.

The liquid crystal base oil typically is present in an amount rangingfrom about 5 to about 99 weight percent or from about 10 to about 95weight percent, preferably from about 20 to about 99 weight percent orfrom about 40 to about 95 weight percent, and more preferably from about50 to about 99 weight percent, based on the total weight of thecomposition.

Preferably, the liquid crystal base oil constitutes the major componentof the engine, or other mechanical component, oil lubricant compositionof the present disclosure and typically is present in an amount rangingfrom greater than about 50 to about 99 weight percent or from about 55to about 95 weight percent, preferably from about 60 to about 99 weightpercent or from about 70 to about 95 weight percent, and more preferablyfrom about 85 to about 95 weight percent, based on the total weight ofthe composition.

Optional Lubricating Oil Base Stocks

A wide range of optional lubricating base oils is known in the art.Optional lubricating base oils that are useful in the present disclosureare natural oils, mineral oils and synthetic oils, and unconventionaloils (or mixtures thereof) can be used unrefined, refined, or rerefined(the latter is also known as reclaimed or reprocessed oil). Unrefinedoils are those obtained directly from a natural or synthetic source andused without added purification. These include shale oil obtaineddirectly from retorting operations, petroleum oil obtained directly fromprimary distillation, and ester oil obtained directly from anesterification process. Refined oils are similar to the oils discussedfor unrefined oils except refined oils are subjected to one or morepurification steps to improve at least one lubricating oil property. Oneskilled in the art is familiar with many purification processes. Theseprocesses include solvent extraction, secondary distillation, acidextraction, base extraction, filtration, and percolation. Rerefined oilsare obtained by processes analogous to refined oils but using an oilthat has been previously used as a feed stock.

Groups I, II, III, IV and V are broad base oil stock categoriesdeveloped and defined by the American Petroleum Institute (APIPublication 1509; www.API.org) to create guidelines for lubricant baseoils. Group I base stocks have a viscosity index of between about 80 to120 and contain greater than about 0.03% sulfur and/or less than about90% saturates. Group II base stocks have a viscosity index of betweenabout 80 to 120, and contain less than or equal to about 0.03% sulfurand greater than or equal to about 90% saturates. Group III stocks havea viscosity index greater than about 120 and contain less than or equalto about 0.03% sulfur and greater than about 90% saturates. Group IVincludes polyalphaolefins (PAO). Group V base stock includes base stocksnot included in Groups I-IV. The table below summarizes properties ofeach of these five groups.

Base Oil Properties Saturates Sulfur Viscosity Index Group I <90and/or >0.03% and ≥80 and <120 Group II ≥90 and ≤0.03% and ≥80 and <120Group III ≥90 and ≤0.03% and ≥120 Group IV polyalphaolefins (PAO) GroupV All other base oil stocks not included in Groups I, II, III or IV

Natural oils include animal oils, vegetable oils (castor oil and lardoil, for example), and mineral oils. Animal and vegetable oilspossessing favorable thermal oxidative stability can be used. Of thenatural oils, mineral oils are preferred. Mineral oils vary widely as totheir crude source, for example, as to whether they are paraffinic,naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal orshale are also useful. Natural oils vary also as to the method used fortheir production and purification, for example, their distillation rangeand whether they are straight run or cracked, hydrorefined, or solventextracted.

Group II and/or Group III hydroprocessed or hydrocracked base stocks arealso well known base stock oils.

Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oilssuch as polymerized and interpolymerized olefins (polybutylenes,polypropylenes, propylene isobutylene copolymers, ethylene-olefincopolymers, and ethylene-alphaolefin copolymers, for example).Polyalphaolefin (PAO) oil base stocks are commonly used synthetichydrocarbon oil. By way of example, PAOs derived from C₈, C₁₀, C₁₂, C₁₄olefins or mixtures thereof may be utilized. See U.S. Pat. Nos.4,956,122; 4,827,064; and 4,827,073.

The number average molecular weights of the PAOs, which are knownmaterials and generally available on a major commercial scale fromsuppliers such as ExxonMobil Chemical Company, Chevron Phillips ChemicalCompany, BP, and others, typically vary from about 250 to about 3,000,although PAO's may be made in viscosities up to about 150 cSt (100° C.).The PAOs are typically comprised of relatively low molecular weighthydrogenated polymers or oligomers of alphaolefins which include, butare not limited to, C₂ to about C₃₂ alphaolefins with the C₈ to aboutC16 alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like,being preferred. The preferred polyalphaolefins are poly-1-octene,poly-1-decene and poly-1-dodecene and mixtures thereof and mixedolefin-derived polyolefins. However, the dimers of higher olefins in therange of C12 to C18 may be used to provide low viscosity base stocks ofacceptably low volatility. Depending on the viscosity grade and thestarting oligomer, the PAOs may be predominantly dimers, trimers andtetramers of the starting olefins, with minor amounts of the lowerand/or higher oligomers, having a viscosity range of 1.5 cSt to 12 cSt.PAO fluids of particular use may include 3 cSt, 3.4 cSt, and/or 3.6 cStand combinations thereof. Mixtures of PAO fluids having a viscosityrange of 1.5 cSt to approximately 150 cSt or more may be used ifdesired. Unless indicated otherwise, all viscosities cited herein aremeasured at 100° C.

The PAO fluids may be conveniently made by the polymerization of analphaolefin in the presence of a polymerization catalyst such as theFriedel-Crafts catalysts including, for example, aluminum trichloride,boron trifluoride or complexes of boron trifluoride with water, alcoholssuch as ethanol, propanol or butanol, carboxylic acids or esters such asethyl acetate or ethyl propionate. For example the methods disclosed byU.S. Pat. Nos. 4,149,178 or 3,382,291 may be conveniently used herein.Other descriptions of PAO synthesis are found in the following U.S. Pat.Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156;4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the C₁₄ toC₁₈ olefins are described in U.S. Pat. No. 4,218,330.

Other useful lubricant oil base stocks include wax isomerate base stocksand base oils, comprising hydroisomerized waxy stocks (e.g. waxy stockssuch as gas oils, slack waxes, fuels hydrocracker bottoms, etc.),hydroisomerized Fischer-Tropsch waxes, Gas-to-Liquids (GTL) base stocksand base oils, and other wax isomerate hydroisomerized base stocks andbase oils, or mixtures thereof. Fischer-Tropsch waxes, the high boilingpoint residues of Fischer-Tropsch synthesis, are highly paraffinichydrocarbons with very low sulfur content. The hydroprocessing used forthe production of such base stocks may use an amorphoushydrocracking/hydroisomerization catalyst, such as one of thespecialized lube hydrocracking (LHDC) catalysts or a crystallinehydrocracking/hydroisomerization catalyst, preferably a zeoliticcatalyst. For example, one useful catalyst is ZSM-48 as described inU.S. Pat. No. 5,075,269, the disclosure of which is incorporated hereinby reference in its entirety. Processes for makinghydrocracked/hydroisomerized distillates andhydrocracked/hydroisomerized waxes are described, for example, in U.S.Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as well as inBritish Patent Nos. 1,429,494; 1,350,257; 1,440,230 and 1,390,359. Eachof the aforementioned patents is incorporated herein in their entirety.Particularly favorable processes are described in European PatentApplication Nos. 464546 and 464547, also incorporated herein byreference. Processes using Fischer-Tropsch wax feeds are described inU.S. Pat. Nos. 4,594,172 and 4,943,672, the disclosures of which areincorporated herein by reference in their entirety.

Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils,and other wax-derived hydroisomerized (wax isomerate) base oils beadvantageously used in the instant disclosure, and may have usefulkinematic viscosities at 100° C. of about 2 cSt to about 50 cSt,preferably about 2 cSt to about 30 cSt, more preferably about 3 cSt toabout 25 cSt, as exemplified by GTL 4 with kinematic viscosity of about4.0 cSt at 100° C. and a viscosity index of about 141. TheseGas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils,and other wax-derived hydroisomerized base oils may have useful pourpoints of about −20° C. or lower, and under some conditions may haveadvantageous pour points of about −25° C. or lower, with useful pourpoints of about −30° C. to about −40° C. or lower. Useful compositionsof Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived baseoils, and wax-derived hydroisomerized base oils are recited in U.S. Pat.Nos. 6,080,301; 6,090,989, and 6,165,949 for example, and areincorporated herein in their entirety by reference.

The hydrocarbyl aromatics can be used as a base oil or base oilcomponent and can be any hydrocarbyl molecule that contains at leastabout 5% of its weight derived from an aromatic moiety such as abenzenoid moiety or naphthenoid moiety, or their derivatives. Thesehydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes, alkylbiphenyls, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenylsulfides, alkylated bis-phenol A, alkylated thiodiphenol, and the like.The aromatic can be mono-alkylated, dialkylated, polyalkylated, and thelike. The aromatic can be mono- or poly-functionalized. The hydrocarbylgroups can also be comprised of mixtures of alkyl groups, alkenylgroups, alkynyl, cycloalkyl groups, cycloalkenyl groups and otherrelated hydrocarbyl groups. The hydrocarbyl groups can range from aboutC₆ up to about C₆₀ with a range of about C₈ to about C₂₀ often beingpreferred. A mixture of hydrocarbyl groups is often preferred, and up toabout three such substituents may be present. The hydrocarbyl group canoptionally contain sulfur, oxygen, and/or nitrogen containingsubstituents. The aromatic group can also be derived from natural(petroleum) sources, provided at least about 5% of the molecule iscomprised of an above-type aromatic moiety. Viscosities at 100° C. ofapproximately 2 cSt to about 50 cSt are preferred, with viscosities ofapproximately 3 cSt to about 20 cSt often being more preferred for thehydrocarbyl aromatic component. In one embodiment, an alkyl naphthalenewhere the alkyl group is primarily comprised of 1-hexadecene is used.Other alkylates of aromatics can be advantageously used. Naphthalene ormethyl naphthalene, for example, can be alkylated with olefins such asoctene, decene, dodecene, tetradecene or higher, mixtures of similarolefins, and the like. Alkylated naphthalene and analogues may alsocomprise compositions with isomeric distribution of alkylating groups onthe alpha and beta carbon positions of the ring structure.

Distribution of groups on the alpha and beta positions of a naphthalenering may range from 100:1 to 1:100, more often 50:1 to 1:50 Usefulconcentrations of hydrocarbyl aromatic in a lubricant oil compositioncan be about 2% to about 25%, preferably about 4% to about 20%, and morepreferably about 4% to about 15%, depending on the application.

Alkylated aromatics such as the hydrocarbyl aromatics of the presentdisclosure may be produced by well-known Friedel-Crafts alkylation ofaromatic compounds. See Friedel-Crafts and Related Reactions, Olah, G.A. (ed.), Inter-science Publishers, New York, 1963. For example, anaromatic compound, such as benzene or naphthalene, is alkylated by anolefin, alkyl halide or alcohol in the presence of a Friedel-Craftscatalyst. See Friedel-Crafts and Related Reactions, Vol. 2, part 1,chapters 14, 17, and 18, See Olah, G. A. (ed.), Inter-sciencePublishers, New York, 1964. Many homogeneous or heterogeneous, solidcatalysts are known to one skilled in the art. The choice of catalystdepends on the reactivity of the starting materials and product qualityrequirements. For example, strong acids such as AlCl₃, BF₃, or HF may beused. In some cases, milder catalysts such as FeCl₃ or SnCl₄ arepreferred. Newer alkylation technology uses zeolites or solid superacids.

Esters comprise a useful base stock. Additive solvency and sealcompatibility characteristics may be secured by the use of esters suchas the esters of dibasic acids with monoalkanols and the polyol estersof monocarboxylic acids. Esters of the former type include, for example,the esters of dicarboxylic acids such as phthalic acid, succinic acid,alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid,suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic aciddimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc.,with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types ofesters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexylfumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate,dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

Particularly useful synthetic esters are those which are obtained byreacting one or more polyhydric alcohols, preferably the hinderedpolyols (such as the neopentyl polyols, e.g., neopentyl glycol,trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylolpropane, pentaerythritol and dipentaerythritol) with alkanoic acidscontaining at least about 4 carbon atoms, preferably C₅ to C₃₀ acidssuch as saturated straight chain fatty acids including caprylic acid,capric acid, lauric acid, myristic acid, palmitic acid, stearic acid,arachic acid, and behenic acid, or the corresponding branched chainfatty acids or unsaturated fatty acids such as oleic acid, or mixturesof any of these materials.

Suitable synthetic ester components include the esters of trimethylolpropane, trimethylol butane, trimethylol ethane, pentaerythritol and/ordipentaerythritol with one or more monocarboxylic acids containing fromabout 5 to about 10 carbon atoms. These esters are widely availablecommercially, for example, the Mobil P-41 and P-51 esters of ExxonMobilChemical Company.

Also useful are esters derived from renewable material such as coconut,palm, rapeseed, soy, sunflower and the like. These esters may bemonoesters, di-esters, polyol esters, complex esters, or mixturesthereof. These esters are widely available commercially, for example,the Mobil P-51 ester of ExxonMobil Chemical Company.

Engine oil formulations containing renewable esters are included in thisdisclosure. For such formulations, the renewable content of the ester istypically greater than about 70 weight percent, preferably more thanabout 80 weight percent and most preferably more than about 90 weightpercent.

Other useful fluids of lubricating viscosity include non-conventional orunconventional base stocks that have been processed, preferablycatalytically, or synthesized to provide high performance lubricationcharacteristics.

Non-conventional or unconventional base stocks/base oils include one ormore of a mixture of base stock(s) derived from one or moreGas-to-Liquids (GTL) materials, as well as isomerate/isodewaxate basestock(s) derived from natural wax or waxy feeds, mineral and ornon-mineral oil waxy feed stocks such as slack waxes, natural waxes, andwaxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxyraffinate, hydrocrackate, thermal crackates, or other mineral, mineraloil, or even non-petroleum oil derived waxy materials such as waxymaterials received from coal liquefaction or shale oil, and mixtures ofsuch base stocks.

GTL materials are materials that are derived via one or more synthesis,combination, transformation, rearrangement, and/ordegradation/deconstructive processes from gaseous carbon-containingcompounds, hydrogen-containing compounds and/or elements as feed stockssuch as hydrogen, carbon dioxide, carbon monoxide, water, methane,ethane, ethylene, acetylene, propane, propylene, propyne, butane,butylenes, and butynes. GTL base stocks and/or base oils are GTLmaterials of lubricating viscosity that are generally derived fromhydrocarbons; for example, waxy synthesized hydrocarbons, that arethemselves derived from simpler gaseous carbon-containing compounds,hydrogen-containing compounds and/or elements as feed stocks. GTL basestock(s) and/or base oil(s) include oils boiling in the lube oil boilingrange (1) separated/fractionated from synthesized GTL materials such as,for example, by distillation and subsequently subjected to a final waxprocessing step which involves either or both of a catalytic dewaxingprocess, or a solvent dewaxing process, to produce lube oils ofreduced/low pour point; (2) synthesized wax isomerates, comprising, forexample, hydrodewaxed or hydroisomerized cat and/or solvent dewaxedsynthesized wax or waxy hydrocarbons; (3) hydrodewaxed orhydroisomerized cat and/or solvent dewaxed Fischer-Tropsch (F-T)material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possibleanalogous oxygenates); preferably hydrodewaxed orhydroisomerized/followed by cat and/or solvent dewaxing dewaxed F-T waxyhydrocarbons, or hydrodewaxed or hydroisomerized/followed by cat (orsolvent) dewaxing dewaxed, F-T waxes, or mixtures thereof.

GTL base stock(s) and/or base oil(s) derived from GTL materials,especially, hydrodewaxed or hydroisomerized/followed by cat and/orsolvent dewaxed wax or waxy feed, preferably F-T material derived basestock(s) and/or base oil(s), are characterized typically as havingkinematic viscosities at 100° C. of from about 2 mm²/s to about 50 mm²/s(ASTM D445). They are further characterized typically as having pourpoints of −5° C. to about −40° C. or lower (ASTM D97). They are alsocharacterized typically as having viscosity indices of about 80 to about140 or greater (ASTM D2270).

In addition, the GTL base stock(s) and/or base oil(s) are typicallyhighly paraffinic (>90% saturates), and may contain mixtures ofmonocycloparaffins and multicycloparaffins in combination withnon-cyclic isoparaffins. The ratio of the naphthenic (i.e.,cycloparaffin) content in such combinations varies with the catalyst andtemperature used. Further, GTL base stock(s) and/or base oil(s)typically have very low sulfur and nitrogen content, generallycontaining less than about 10 ppm, and more typically less than about 5ppm of each of these elements. The sulfur and nitrogen content of GTLbase stock(s) and/or base oil(s) obtained from F-T material, especiallyF-T wax, is essentially nil. In addition, the absence of phosphorus andaromatics make this materially especially suitable for the formulationof low SAP products.

The term GTL base stock and/or base oil and/or wax isomerate base stockand/or base oil is to be understood as embracing individual fractions ofsuch materials of wide viscosity range as recovered in the productionprocess, mixtures of two or more of such fractions, as well as mixturesof one or two or more low viscosity fractions with one, two or morehigher viscosity fractions to produce a blend wherein the blend exhibitsa target kinematic viscosity.

The GTL material, from which the GTL base stock(s) and/or base oil(s)is/are derived is preferably an F-T material (i.e., hydrocarbons, waxyhydrocarbons, wax).

Optional base oils for use in the formulated lubricating oils useful inthe present disclosure are any of the variety of oils corresponding toAPI Group I, Group II, Group III, Group IV, and Group V oils andmixtures thereof, preferably API Group II, Group III, Group IV, andGroup V oils and mixtures thereof, more preferably the Group III toGroup V base oils due to their exceptional volatility, stability,viscometric and cleanliness features. Minor quantities of Group I stock,such as the amount used to dilute additives for blending into formulatedlube oil products, can be tolerated but should be kept to a minimum,i.e. amounts only associated with their use as diluent/carrier oil foradditives used on an “as-received” basis. Even in regard to the Group IIstocks, it is preferred that the Group II stock be in the higher qualityrange associated with that stock, i.e. a Group II stock having aviscosity index in the range 100<VI<120.

The optional base oil is typically is present in an amount ranging fromabout 6 to about 49 weight percent or from about 6 to about 45 weightpercent, preferably from about 10 to about 49 weight percent or fromabout 20 to about 45 weight percent, and more preferably from about 25to about 45 weight percent, based on the total weight of thecomposition. The optional base oil may be selected from any of thesynthetic or natural oils typically used as crankcase lubricating oilsfor spark-ignited and compression-ignited engines. The optional base oilconveniently has a kinematic viscosity, according to ASTM standards, ofabout 2.5 cSt to about 18 cSt (or mm² /s) at 100° C. and preferably ofabout 2.5 cSt to about 12.5 cSt (or mm² /s) at 100° C., often morepreferably from about 2.5 cSt to about 10 cSt. Mixtures of synthetic andnatural base oils may be used if desired. Bi-modal, tri-modal, andadditional combinations of mixtures of Group I, II, III, IV, and/or Vbase stocks may be used if desired.

Additives

The formulated lubricating oil useful in the present disclosure mayadditionally contain one or more of the other commonly used lubricatingoil performance additives including but not limited to antiwearadditives, dispersants, detergents, viscosity modifiers, corrosioninhibitors, rust inhibitors, metal deactivators, extreme pressureadditives, anti-seizure agents, wax modifiers, viscosity modifiers,fluid-loss additives, seal compatibility agents, lubricity agents,anti-staining agents, chromophoric agents, defoamants, demulsifiers,densifiers, wetting agents, gelling agents, tackiness agents, colorants,and others. For a review of many commonly used additives, see Klamann inLubricants and Related Products, Verlag Chemie, Deerfield Beach, Fla.;ISBN 0-89573-177-0. Reference is also made to “Lubricant Additives” byM. W. Ranney, published by Noyes Data Corporation of Parkridge, N.J.(1973); see also U.S. Pat. No. 7,704,930, the disclosure of which isincorporated herein in its entirety. These additives are commonlydelivered with varying amounts of diluent oil, that may range from 5weight percent to 50 weight percent.

The additives useful in this disclosure do not have to be soluble in thelubricating oils. Insoluble additives in oil can be dispersed in thelubricating oils of this disclosure.

The types and quantities of performance additives used in combinationwith the instant disclosure in lubricant compositions are not limited bythe examples shown herein as illustrations.

Dispersants

During engine operation, oil-insoluble oxidation byproducts areproduced. Dispersants help keep these byproducts in solution, thusdiminishing their deposition on metal surfaces. Dispersants used in theformulation of the lubricating oil may be ashless or ash-forming innature. Preferably, the dispersant is ashless. So called ashlessdispersants are organic materials that form substantially no ash uponcombustion. For example, non-metal-containing or borated metal-freedispersants are considered ashless. In contrast, metal-containingdetergents discussed above form ash upon combustion.

Suitable dispersants typically contain a polar group attached to arelatively high molecular weight hydrocarbon chain. The polar grouptypically contains at least one element of nitrogen, oxygen, orphosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

A particularly useful class of dispersants are the (poly)alkenylsuccinicderivatives, typically produced by the reaction of a long chainhydrocarbyl substituted succinic compound, usually a hydrocarbylsubstituted succinic anhydride, with a polyhydroxy or polyaminocompound. The long chain hydrocarbyl group constituting the oleophilicportion of the molecule which confers solubility in the oil, is normallya polyisobutylene group. Many examples of this type of dispersant arewell known commercially and in the literature. Exemplary U.S. patentsdescribing such dispersants are U.S. Pat. Nos. 3,172,892; 3,2145,707;3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012;3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersantare described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025;3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574;3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250;3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. Afurther description of dispersants may be found, for example, inEuropean Patent Application No. 471 071, to which reference is made forthis purpose.

Hydrocarbyl-substituted succinic acid and hydrocarbyl-substitutedsuccinic anhydride derivatives are useful dispersants. In particular,succinimide, succinate esters, or succinate ester amides prepared by thereaction of a hydrocarbon-substituted succinic acid compound preferablyhaving at least 50 carbon atoms in the hydrocarbon substituent, with atleast one equivalent of an alkylene amine are particularly useful.

Succinimides are formed by the condensation reaction between hydrocarbylsubstituted succinic anhydrides and amines. Molar ratios can varydepending on the polyamine. For example, the molar ratio of hydrocarbylsubstituted succinic anhydride to TEPA can vary from about 1:1 to about5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936;3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616, 3,948,800;and Canada Patent No. 1,094,044.

Succinate esters are formed by the condensation reaction betweenhydrocarbyl substituted succinic anhydrides and alcohols or polyols.Molar ratios can vary depending on the alcohol or polyol used. Forexample, the condensation product of a hydrocarbyl substituted succinicanhydride and pentaerythritol is a useful dispersant.

Succinate ester amides are formed by condensation reaction betweenhydrocarbyl substituted succinic anhydrides and alkanol amines. Forexample, suitable alkanol amines include ethoxylatedpolyalkylpolyamines, propoxylated polyalkylpolyamines andpolyalkenylpolyamines such as polyethylene polyamines. One example ispropoxylated hexamethylenediamine. Representative examples are shown inU.S. Pat. No. 4,426,305.

The molecular weight of the hydrocarbyl substituted succinic anhydridesused in the preceding paragraphs will typically range between 800 and2,500 or more. The above products can be post-reacted with variousreagents such as sulfur, oxygen, formaldehyde, carboxylic acids such asoleic acid. The above products can also be post reacted with boroncompounds such as boric acid, borate esters or highly borateddispersants, to form borated dispersants generally having from about 0.1to about 5 moles of boron per mole of dispersant reaction product.

Mannich base dispersants are made from the reaction of alkylphenols,formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which isincorporated herein by reference. Process aids and catalysts, such asoleic acid and sulfonic acids, can also be part of the reaction mixture.Molecular weights of the alkylphenols range from 800 to 2,500.Representative examples are shown in U.S. Pat. Nos. 3,697,574;3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

Typical high molecular weight aliphatic acid modified Mannichcondensation products useful in this disclosure can be prepared fromhigh molecular weight alkyl-substituted hydroxyaromatics or HNR₂group-containing reactants.

Hydrocarbyl substituted amine ashless dispersant additives are wellknown to one skilled in the art; see, for example, U.S. Pat. Nos.3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and 5,084,197.

Preferred dispersants include borated and non-borated succinimides,including those derivatives from mono-succinimides, bis-succinimides,and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbylsuccinimide is derived from a hydrocarbylene group such aspolyisobutylene having a Mn of from about 500 to about 5000, or fromabout 1000 to about 3000, or about 1000 to about 2000, or a mixture ofsuch hydrocarbylene groups, often with high terminal vinylic groups.Other preferred dispersants include succinic acid-esters and amides,alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives,and other related components.

Polymethacrylate or polyacrylate derivatives are another class ofdispersants. These dispersants are typically prepared by reacting anitrogen containing monomer and a methacrylic or acrylic acid esterscontaining 5 -25 carbon atoms in the ester group. Representativeexamples are shown in U.S. Pat. Nos. 2,100,993, and 6,323,164.Polymethacrylate and polyacrylate dispersants are normally used asmultifunctional viscosity modifiers. The lower molecular weight versionscan be used as lubricant dispersants or fuel detergents.

Illustrative preferred dispersants useful in this disclosure includethose derived from polyalkenyl-substituted mono- or dicarboxylic acid,anhydride or ester, which dispersant has a polyalkenyl moiety with anumber average molecular weight of at least 900 and from greater than1.3 to 1.7, preferably from greater than 1.3 to 1.6, most preferablyfrom greater than 1.3 to 1.5, functional groups (mono- or dicarboxylicacid producing moieties) per polyalkenyl moiety (a medium functionalitydispersant). Functionality (F) can be determined according to thefollowing formula:

F=(SAP×Mn)/((112,200×A.I.)−(SAP×98))

wherein SAP is the saponification number (i.e., the number of milligramsof KOH consumed in the complete neutralization of the acid groups in onegram of the succinic-containing reaction product, as determinedaccording to ASTM D94); Mn is the number average molecular weight of thestarting olefin polymer; and A.I. is the percent active ingredient ofthe succinic-containing reaction product (the remainder being unreactedolefin polymer, succinic anhydride and diluent).

The polyalkenyl moiety of the dispersant may have a number averagemolecular weight of at least 900, suitably at least 1500, preferablybetween 1800 and 3000, such as between 2000 and 2800, more preferablyfrom about 2100 to 2500, and most preferably from about 2200 to about2400. The molecular weight of a dispersant is generally expressed interms of the molecular weight of the polyalkenyl moiety. This is becausethe precise molecular weight range of the dispersant depends on numerousparameters including the type of polymer used to derive the dispersant,the number of functional groups, and the type of nucleophilic groupemployed.

Polymer molecular weight, specifically Mn, can be determined by variousknown techniques. One convenient method is gel permeation chromatography(GPC), which additionally provides molecular weight distributioninformation (see W. W. Yau, J. J. Kirkland and D. D. Bly, “Modern SizeExclusion Liquid Chromatography”, John Wiley and Sons, New York, 1979).Another useful method for determining molecular weight, particularly forlower molecular weight polymers, is vapor pressure osmometry (e.g., ASTMD3592).

The polyalkenyl moiety in a dispersant preferably has a narrow molecularweight distribution (MWD), also referred to as polydispersity, asdetermined by the ratio of weight average molecular weight (M_(w)) tonumber average molecular weight (M_(n)). Polymers having a M_(w)/M_(n)of less than 2.2, preferably less than 2.0, are most desirable. Suitablepolymers have a polydispersity of from about 1.5 to 2.1, preferably fromabout 1.6 to about 1.8.

Suitable polyalkenes employed in the formation of the dispersantsinclude homopolymers, interpolymers or lower molecular weighthydrocarbons. One family of such polymers comprise polymers of ethyleneand/or at least one C₃ to C₂ alpha-olefin having the formula H₂C═CHR¹wherein R¹ is a straight or branched chain alkyl radical comprising 1 to26 carbon atoms and wherein the polymer contains carbon-to-carbonunsaturation, and a high degree of terminal ethenylidene unsaturation.Preferably, such polymers comprise interpolymers of ethylene and atleast one alpha-olefin of the above formula, wherein R¹ is alkyl of from1 to 18 carbon atoms, and more preferably is alkyl of from 1 to 8 carbonatoms, and more preferably still of from 1 to 2 carbon atoms.

Another useful class of polymers is polymers prepared by cationicpolymerization of monomers such as isobutene and styrene. Commonpolymers from this class include polyisobutenes obtained bypolymerization of a C4 refinery stream having a butene content of 35 to75% by wt., and an isobutene content of 30 to 60% by wt. A preferredsource of monomer for making poly-n-butenes is petroleum feedstreamssuch as Raffinate II. These feedstocks are disclosed in the art such asin U.S. Pat. No. 4,952,739. A preferred embodiment utilizespolyisobutylene prepared from a pure isobutylene stream or a Raffinate Istream to prepare reactive isobutylene polymers with terminal vinylideneolefins. Polyisobutene polymers that may be employed are generally basedon a polymer chain of from 1500 to 3000.

The dispersant(s) are preferably non-polymeric (e.g., mono- orbis-succinimides). Such dispersants can be prepared by conventionalprocesses such as disclosed in U.S. Patent Application Publication No.2008/0020950, the disclosure of which is incorporated herein byreference.

The dispersant(s) can be borated by conventional means, as generallydisclosed in U.S. Pat. Nos. 3,087,936, 3,254,025 and 5,430,105.

Such dispersants may be used in an amount of about 0.01 to 20 weightpercent or 0.01 to 10 weight percent, preferably about 0.5 to 8 weightpercent, or more preferably 0.5 to 4 weight percent. Or such dispersantsmay be used in an amount of about 2 to 12 weight percent, preferablyabout 4 to 10 weight percent, or more preferably 6 to 9 weight percent.On an active ingredient basis, such additives may be used in an amountof about 0.06 to 14 weight percent, preferably about 0.3 to 6 weightpercent. The hydrocarbon portion of the dispersant atoms can range fromC₆₀ to C₁₀₀₀, or from C₇₀ to C₃₀₀, or from C₇₀ to C₂₀₀. Thesedispersants may contain both neutral and basic nitrogen, and mixtures ofboth. Dispersants can be end-capped by borates and/or cyclic carbonates.Nitrogen content in the finished oil can vary from about 200 ppm byweight to about 2000 ppm by weight, preferably from about 200 ppm byweight to about 1200 ppm by weight. Basic nitrogen can vary from about100 ppm by weight to about 1000 ppm by weight, preferably from about 100ppm by weight to about 600 ppm by weight.

Dispersants as described herein are beneficially useful with thecompositions of this disclosure and substitute for some or all of thesurfactants of this disclosure. Further, in one embodiment, preparationof the compositions of this disclosure using one or more dispersants isachieved by combining ingredients of this disclosure, plus optional basestocks and lubricant additives, in a mixture at a temperature above themelting point of such ingredients, particularly that of the one or moreM-carboxylates (M═H, metal, two or more metals, mixtures thereof).

As used herein, the dispersant concentrations are given on an “asdelivered” basis. Typically, the active dispersant is delivered with aprocess oil. The “as delivered” dispersant typically contains from about20 weight percent to about 80 weight percent, or from about 40 weightpercent to about 60 weight percent, of active dispersant in the “asdelivered” dispersant product.

Detergents

Illustrative detergents useful in this disclosure include, for example,alkali metal detergents, alkaline earth metal detergents, or mixtures ofone or more alkali metal detergents and one or more alkaline earth metaldetergents. A typical detergent is an anionic material that contains along chain hydrophobic portion of the molecule and a smaller anionic oroleophobic hydrophilic portion of the molecule. The anionic portion ofthe detergent is typically derived from an organic acid such as asulfur-containing acid, carboxylic acid (e.g., salicylic acid),phosphorus-containing acid, phenol, or mixtures thereof. The counterionis typically an alkaline earth or alkali metal. The detergent can beoverbased as described herein.

The detergent is preferably a metal salt of an organic or inorganicacid, a metal salt of a phenol, or mixtures thereof. The metal ispreferably selected from an alkali metal, an alkaline earth metal, andmixtures thereof. The organic or inorganic acid is selected from analiphatic organic or inorganic acid, a cycloaliphatic organic orinorganic acid, an aromatic organic or inorganic acid, and mixturesthereof.

The metal is preferably selected from an alkali metal, an alkaline earthmetal, and mixtures thereof. More preferably, the metal is selected fromcalcium (Ca), magnesium (Mg), and mixtures thereof.

The organic acid or inorganic acid is preferably selected from asulfur-containing acid, a carboxylic acid, a phosphorus-containing acid,and mixtures thereof.

Preferably, the metal salt of an organic or inorganic acid or the metalsalt of a phenol comprises calcium phenate, calcium sulfonate, calciumsalicylate, magnesium phenate, magnesium sulfonate, magnesiumsalicylate, an overbased detergent, and mixtures thereof.

Salts that contain a substantially stochiometric amount of the metal aredescribed as neutral salts and have a total base number (TBN, asmeasured by ASTM D2896) of from 0 to 80. Many compositions areoverbased, containing large amounts of a metal base that is achieved byreacting an excess of a metal compound (a metal hydroxide or oxide, forexample) with an acidic gas (such as carbon dioxide). Useful detergentscan be neutral, mildly overbased, or highly overbased. These detergentscan be used in mixtures of neutral, overbased, highly overbased calciumsalicylate, sulfonates, phenates and/or magnesium salicylate,sulfonates, phenates. The TBN ranges can vary from low, medium to highTBN products, including as low as 0 to as high as 600. Preferably theTBN delivered by the detergent is between 1 and 20. More preferablybetween 1 and 12. Mixtures of low, medium, high TBN can be used, alongwith mixtures of calcium and magnesium metal based detergents, andincluding sulfonates, phenates, salicylates, and carboxylates. Adetergent mixture with a metal ratio of 1, in conjunction of a detergentwith a metal ratio of 2, and as high as a detergent with a metal ratioof 5, can be used. Borated detergents can also be used.

Alkaline earth phenates are another useful class of detergent. Thesedetergents can be made by reacting alkaline earth metal hydroxide oroxide (CaO, Ca(OH)₂, BaO, Ba(OH)₂, MgO, Mg(OH)₂, for example) with analkyl phenol or sulfurized alkylphenol. Useful alkyl groups includestraight chain or branched C₁-C₃₀ alkyl groups, preferably, C₄-C₂₀ ormixtures thereof. Examples of suitable phenols include isobutylphenol,2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It shouldbe noted that starting alkylphenols may contain more than one alkylsubstituent that are each independently straight chain or branched andcan be used from 0.5 to 6 weight percent. When a non-sulfurizedalkylphenol is used, the sulfurized product may be obtained by methodswell known in the art. These methods include heating a mixture ofalkylphenol and sulfurizing agent (including elemental sulfur, sulfurhalides such as sulfur dichloride, and the like) and then reacting thesulfurized phenol with an alkaline earth metal base.

In accordance with this disclosure, metal salts of carboxylic acids arepreferred detergents. These carboxylic acid detergents may be preparedby reacting a basic metal compound with at least one carboxylic acid andremoving free water from the reaction product. These compounds may beoverbased to produce the desired TBN level. Detergents made fromsalicylic acid are one preferred class of detergents derived fromcarboxylic acids. Useful salicylates include long chain alkylsalicylates. One useful family of compos

where R is an alkyl group having 1 to about 30 carbon atoms, n is aninteger from 1 to 4, and M is an alkaline earth metal. Preferred Rgroups are alkyl chains of at least C₁₁, preferably C₁₃ or greater. Rmay be optionally substituted with substituents that do not interferewith the detergent's function. M is preferably, calcium, magnesium,barium, or mixtures thereof. More preferably, M is calcium.

Hydrocarbyl-substituted salicylic acids may be prepared from phenols bythe Kolbe reaction (see U.S. Pat. No. 3,595,791). The metal salts of thehydrocarbyl-substituted salicylic acids may be prepared by doubledecomposition of a metal salt in a polar solvent such as water oralcohol.

Alkaline earth metal phosphates are also used as detergents and areknown in the art.

Detergents may be simple detergents or what is known as hybrid orcomplex detergents. The latter detergents can provide the properties oftwo detergents without the need to blend separate materials. See U.S.Pat. No. 6,034,039.

Preferred detergents include calcium sulfonates, magnesium sulfonates,calcium salicylates, magnesium salicylates, calcium phenates, magnesiumphenates, and other related components (including borated detergents),and mixtures thereof. Preferred mixtures of detergents include magnesiumsulfonate and calcium salicylate, magnesium sulfonate and calciumsulfonate, magnesium sulfonate and calcium phenate, calcium phenate andcalcium salicylate, calcium phenate and calcium sulfonate, calciumphenate and magnesium salicylate, calcium phenate and magnesium phenate.Overbased detergents are also preferred.

The detergent concentration in the lubricating oils of this disclosurecan range from about 0.5 to about 6.0 weight percent, preferably about0.6 to 5.0 weight percent, and more preferably from about 0.8 weightpercent to about 4.0 weight percent, based on the total weight of thelubricating oil.

As used herein, the detergent concentrations are given on an “asdelivered” basis. Typically, the active detergent is delivered with aprocess oil. The “as delivered” detergent typically contains from about20 weight percent to about 100 weight percent, or from about 40 weightpercent to about 60 weight percent, of active detergent in the “asdelivered” detergent product.

Antiwear Additives

A metal alkylthiophosphate and more particularly a metal dialkyl dithiophosphate in which the metal constituent is zinc, or zinc dialkyl dithiophosphate (ZDDP) can be a useful component of the lubricating oils ofthis disclosure. ZDDP can be derived from primary alcohols, secondaryalcohols or mixtures thereof. ZDDP compounds generally are of theformula

Zn[SP(S)(OR¹)(OR²)]₂

where R¹ and R² are C₁-C₁₈ alkyl groups, preferably C₂-C₁₂ alkyl groups.These alkyl groups may be straight chain or branched. Alcohols used inthe ZDDP can be propanol, 2-propanol, butanol, secondary butanol,pentanols, hexanols such as 4-methyl-2-pentanol, n-hexanol, n-octanol,2-ethyl hexanol, alkylated phenols, and the like. Mixtures of secondaryalcohols or of primary and secondary alcohol can be preferred. Alkylaryl groups may also be used.

Preferable zinc dithiophosphates which are commercially availableinclude secondary zinc dithiophosphates such as those available from forexample. The Lubrizol Corporation under the trade designations “LZ677A”, “LZ 1095” and “LZ 1371”, from for example Chevron Oronite underthe trade designation “OLOA 262” and from for example Afton Chemicalunder the trade designation “HITEC 7169”.

The ZDDP is typically used in amounts of from about 0.3 weight percentto about 1.5 weight percent, preferably from about 0.4 weight percent toabout 1.2 weight percent, more preferably from about 0.5 weight percentto about 1.0 weight percent, and even more preferably from about 0.6weight percent to about 0.8 weight percent, based on the total weight ofthe lubricating oil, although more or less can often be usedadvantageously. Preferably, the ZDDP is a secondary ZDDP and present inan amount of from about 0.6 to 1.0 weight percent of the total weight ofthe lubricating oil.

Viscosity Modifiers

Viscosity modifiers (also known as viscosity index improvers (VIimprovers), and viscosity improvers) can be included in the lubricantcompositions of this disclosure.

Viscosity modifiers provide lubricants with high and low temperatureoperability. These additives impart shear stability at elevatedtemperatures and acceptable viscosity at low temperatures.

Suitable viscosity modifiers include high molecular weight hydrocarbons,polyesters and viscosity modifier dispersants that function as both aviscosity modifier and a dispersant. Typical molecular weights of thesepolymers are between about 10,000 to 1,500,000, more typically about20,000 to 1,200,000, and even more typically between about 50,000 and1,000,000.

Examples of suitable viscosity modifiers are linear or star-shapedpolymers and copolymers of methacrylate, butadiene, olefins, oralkylated styrenes. Polyisobutylene is a commonly used viscositymodifier. Another suitable viscosity modifier is polymethacrylate(copolymers of various chain length alkyl methacrylates, for example),some formulations of which also serve as pour point depressants. Othersuitable viscosity modifiers include copolymers of ethylene andpropylene, hydrogenated block copolymers of styrene and isoprene, andpolyacrylates (copolymers of various chain length acrylates, forexample). Specific examples include styrene-isoprene orstyrene-butadiene based polymers of 50,000 to 200,000 molecular weight.

Olefin copolymers are commercially available from Chevron OroniteCompany LLC under the trade designation “PARATONE®” (such as “PARATONE®8921” and “PARATONE® 8941”); from Afton Chemical Corporation under thetrade designation “HiTEC®” (such as “HiTEC® 5850B”; and from TheLubrizol Corporation under the trade designation “Lubrizol® 7067C”.Hydrogenated polyisoprene star polymers are commercially available fromInfineum International Limited, e.g., under the trade designation“SV200” and “SV600”. Hydrogenated diene-styrene block copolymers arecommercially available from Infineum International Limited, e.g., underthe trade designation “SV 50”.

The polymethacrylate or polyacrylate polymers can be linear polymerswhich are available from Evnoik Industries under the trade designation“Viscoplex®” (e.g., Viscoplex 6-954) or star polymers which areavailable from Lubrizol Corporation under the trade designation Asteric™(e.g., Lubrizol 87708 and Lubrizol 87725).

Illustrative vinyl aromatic-containing polymers useful in thisdisclosure may be derived predominantly from vinyl aromatic hydrocarbonmonomer. Illustrative vinyl aromatic-containing copolymers useful inthis disclosure may be represented by the following general formula:

A-B

wherein A is a polymeric block derived predominantly from vinyl aromatichydrocarbon monomer, and B is a polymeric block derived predominantlyfrom conjugated diene monomer.

In an embodiment of this disclosure, the viscosity modifiers may be usedin an amount of less than about 10 weight percent, preferably less thanabout 7 weight percent, more preferably less than about 4 weightpercent, and in certain instances, may be used at less than 2 weightpercent, preferably less than about 1 weight percent, and morepreferably less than about 0.5 weight percent, based on the total weightof the formulated oil or lubricating engine oil. Viscosity modifiers aretypically added as concentrates, in large amounts of diluent oil.

As used herein, the viscosity modifier concentrations are given on an“as delivered” basis. Typically, the active polymer is delivered with adiluent oil. The “as delivered” viscosity modifier typically containsfrom 20 weight percent to 75 weight percent of an active polymer forpolymethacrylate or polyacrylate polymers, or from 8 weight percent to20 weight percent of an active polymer for olefin copolymers,hydrogenated polyisoprene star polymers, or hydrogenated diene-styreneblock copolymers, in the “as delivered” polymer concentrate.

Antioxidants

Antioxidants retard the oxidative degradation of base oils duringservice. Such degradation may result in deposits on metal surfaces, thepresence of sludge, or a viscosity increase in the lubricant. Oneskilled in the art knows a wide variety of oxidation inhibitors that areuseful in lubricating oil compositions. See, Klamann in Lubricants andRelated Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197,for example.

Useful antioxidants include hindered phenols. These phenolicantioxidants may be ashless (metal-free) phenolic compounds or neutralor basic metal salts of certain phenolic compounds. Typical phenolicantioxidant compounds are the hindered phenolics which are the oneswhich contain a sterically hindered hydroxyl group, and these includethose derivatives of dihydroxy aryl compounds in which the hydroxylgroups are in the o- or p-position to each other. Typical phenolicantioxidants include the hindered phenols substituted with C6+alkylgroups and the alkylene coupled derivatives of these hindered phenols.Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol;2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol;2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol;2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecylphenol. Other useful hindered mono-phenolic antioxidants may include forexample hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.Bis-phenolic antioxidants may also be advantageously used in combinationwith the instant disclosure. Examples of ortho-coupled phenols include:2,2′-bis(4-heptyl-6-t-butyl-phenol); 2,2′-bis(4-octyl-6-t-butyl-phenol);and 2,2′-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenolsinclude for example 4,4′-bis(2,6-di-t-butyl phenol) and4,4′-methylene-bis(2,6-di-t-butyl phenol).

Effective amounts of one or more catalytic antioxidants may also beused. The catalytic antioxidants comprise an effective amount of a) oneor more oil soluble polymetal organic compounds; and, effective amountsof b) one or more substituted N,N′-diaryl-o-phenylenediamine compoundsor c) one or more hindered phenol compounds; or a combination of both b)and c). Catalytic antioxidants are more fully described in U.S. Pat. No.8, 048,833, herein incorporated by reference in its entirety.

Non-phenolic oxidation inhibitors which may be used include aromaticamine antioxidants and these may be used either as such or incombination with phenolics. Typical examples of non-phenolicantioxidants include: alkylated and non-alkylated aromatic amines suchas aromatic monoamines of the formula R⁸R⁹R¹⁰N where R⁸ is an aliphatic,aromatic or substituted aromatic group, R⁹ is an aromatic or asubstituted aromatic group, and R¹⁰ is H, alkyl, aryl or R¹¹S(O)_(x)R¹²where R¹¹ is an alkylene, alkenylene, or aralkylene group, R¹² is ahigher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1or 2. The aliphatic group R⁸ may contain from 1 to about 20 carbonatoms, and preferably contains from about 6 to 12 carbon atoms. Thealiphatic group is a saturated aliphatic group. Preferably, both R⁸ andR⁹ are aromatic or substituted aromatic groups, and the aromatic groupmay be a fused ring aromatic group such as naphthyl. Aromatic groups R⁸and R⁹ may be joined together with other groups such as S.

Typical aromatic amines antioxidants have alkyl substituent groups of atleast about 6 carbon atoms. Examples of aliphatic groups include hexyl,heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups willnot contain more than about 14 carbon atoms. The general types of amineantioxidants useful in the present compositions include diphenylamines,phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenylphenylene diamines. Mixtures of two or more aromatic amines are alsouseful. Polymeric amine antioxidants can also be used. Particularexamples of aromatic amine antioxidants useful in the present disclosureinclude: p,p′-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine;phenyl-alphanaphthylamine; and p-octylphenyl-alpha-naphthylamine.

Sulfurized alkyl phenols and alkali or alkaline earth metal saltsthereof also are useful antioxidants.

Preferred antioxidants include hindered phenols, arylamines. Theseantioxidants may be used individually by type or in combination with oneanother. Such additives may be used in an amount of about 0.01 to 5weight percent, preferably about 0.01 to 1.5 weight percent, morepreferably zero to less than 1.5 weight percent, more preferably zero toless than 1 weight percent.

Pour Point Depressants (PPDs)

Conventional pour point depressants (also known as lube oil flowimprovers) may be added to the compositions of the present disclosure ifdesired. These pour point depressant may be added to lubricatingcompositions of the present disclosure to lower the minimum temperatureat which the fluid will flow or can be poured. Examples of suitable pourpoint depressants include polymethacrylates, polyacrylates,polyarylamides, condensation products of haloparaffin waxes and aromaticcompounds, vinyl carboxylate polymers, and terpolymers ofdialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers.U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479;2,666,746; 2,721,877; 2,721,878; and 3,250,715 describe useful pourpoint depressants and/or the preparation thereof. Such additives may beused in an amount of about 0.01 to 5 weight percent, preferably about0.01 to 1.5 weight percent.

Seal Compatibility Agents

Seal compatibility agents help to swell elastomeric seals by causing achemical reaction in the fluid or physical change in the elastomer.Suitable seal compatibility agents for lubricating oils include organicphosphates, aromatic esters, aromatic hydrocarbons, esters (butylbenzylphthalate, for example), and polybutenyl succinic anhydride. Suchadditives may be used in an amount of about 0.01 to 3 weight percent,preferably about 0.01 to 2 weight percent.

Antifoam Agents

Anti-foam agents may advantageously be added to lubricant compositions.These agents retard the formation of stable foams. Silicones and organicpolymers are typical anti-foam agents. For example, polysiloxanes, suchas silicon oil or polydimethyl siloxane, provide antifoam properties.Anti-foam agents are commercially available and may be used inconventional minor amounts along with other additives such asdemulsifiers; usually the amount of these additives combined is lessthan 1 weight percent and often less than 0.1 weight percent.

Inhibitors and Antirust Additives

Antirust additives (or corrosion inhibitors) are additives that protectlubricated metal surfaces against chemical attack by water or othercontaminants. A wide variety of these are commercially available.

One type of antirust additive is a polar compound that wets the metalsurface preferentially, protecting it with a film of oil. Another typeof antirust additive absorbs water by incorporating it in a water-in-oilemulsion so that only the oil touches the metal surface. Yet anothertype of antirust additive chemically adheres to the metal to produce anon-reactive surface. Examples of suitable additives include zincdithiophosphates, metal phenolates, basic metal sulfonates, fatty acidsand amines. Such additives may be used in an amount of about 0.01 to 5weight percent, preferably about 0.01 to 1.5 weight percent.

Friction Modifiers

A friction modifier is any material or materials that can alter thecoefficient of friction of a surface lubricated by any lubricant orfluid containing such material(s). Friction modifiers, also known asfriction reducers, or lubricity agents or oiliness agents, and othersuch agents that change the ability of base oils, formulated lubricantcompositions, or functional fluids, to modify the coefficient offriction of a lubricated surface may be effectively used in combinationwith the base oils or lubricant compositions of the present disclosureif desired. Friction modifiers that lower the coefficient of frictionare particularly advantageous in combination with the base oils and lubecompositions of this disclosure.

Illustrative friction modifiers may include, for example, organometalliccompounds or materials, or mixtures thereof. Illustrative organometallicfriction modifiers useful in the lubricating engine oil formulations ofthis disclosure include, for example, molybdenum amine, molybdenumdiamine, an organotungstenate, a molybdenum dithiocarbamate, molybdenumdithiophosphates, molybdenum amine complexes, molybdenum carboxylates,and the like, and mixtures thereof. Similar tungsten based compounds maybe preferable.

Other illustrative friction modifiers useful in the lubricating engineoil formulations of this disclosure include, for example, alkoxylatedfatty acid esters, alkanolamides, polyol fatty acid esters, boratedglycerol fatty acid esters, fatty alcohol ethers, and mixtures thereof.

Illustrative alkoxylated fatty acid esters include, for example,polyoxyethylene stearate, fatty acid polyglycol ester, and the like.These can include polyoxypropylene stearate, polyoxybutylene stearate,polyoxyethylene isosterate, polyoxypropylene isostearate,polyoxyethylene palmitate, and the like.

Illustrative alkanolamides include, for example, lauric aciddiethylalkanolamide, palmic acid diethylalkanolamide, and the like.These can include oleic acid diethyalkanolamide, stearic aciddiethylalkanolamide, oleic acid diethylalkanolamide, polyethoxylatedhydrocarbylamides, polypropoxylated hydrocarbylamides, and the like.

Illustrative polyol fatty acid esters include, for example, glycerolmono-oleate, saturated mono-, di-, and tri-glyceride esters, glycerolmono-stearate, and the like. These can include polyol esters,hydroxyl-containing polyol esters, and the like.

Illustrative borated glycerol fatty acid esters include, for example,borated glycerol mono-oleate, borated saturated mono-, di-, andtri-glyceride esters, borated glycerol mono-sterate, and the like. Inaddition to glycerol polyols, these can include trimethylolpropane,pentaerythritol, sorbitan, and the like. These esters can be polyolmonocarboxylate esters, polyol dicarboxylate esters, and on occasionpolyoltricarboxylate esters. Preferred can be the glycerol mono-oleates,glycerol dioleates, glycerol trioleates, glycerol monostearates,glycerol distearates, and glycerol tristearates and the correspondingglycerol monopalmitates, glycerol dipalmitates, and glyceroltripalmitates, and the respective isostearates, linoleates, and thelike. On occasion the glycerol esters can be preferred as well asmixtures containing any of these. Ethoxylated, propoxylated, butoxylatedfatty acid esters of polyols, especially using glycerol as underlyingpolyol can be preferred.

Illustrative fatty alcohol ethers include, for example, stearyl ether,myristyl ether, and the like. Alcohols, including those that have carbonnumbers from C₃ to C₅₀, can be ethoxylated, propoxylated, or butoxylatedto form the corresponding fatty alkyl ethers. The underlying alcoholportion can preferably be stearyl, myristyl, C₁₁-C₁₃ hydrocarbon, oleyl,isosteryl, and the like.

The lubricating oils of this disclosure exhibit desired properties,e.g., wear control, in the presence or absence of a friction modifier.

Useful concentrations of friction modifiers may range from 0.01 weightpercent to 5 weight percent, or about 0.1 weight percent to about 2.5weight percent, or about 0.1 weight percent to about 1.5 weight percent,or about 0.1 weight percent to about 1 weight percent. Concentrations ofmolybdenum-containing materials are often described in terms of Mo metalconcentration. Advantageous concentrations of Mo may range from 25 ppmto 700 ppm or more, and often with a preferred range of 50-200 ppm.Friction modifiers of all types may be used alone or in mixtures withthe materials of this disclosure. Often mixtures of two or more frictionmodifiers, or mixtures of friction modifier(s) with alternate surfaceactive material(s), are also desirable.

When lubricating oil compositions contain one or more of the additivesdiscussed above, the additive(s) are blended into the composition in anamount sufficient for it to perform its intended function. Typicalamounts of such additives useful in the present disclosure are shown inTable 1 below.

It is noted that many of the additives are shipped from the additivemanufacturer as a concentrate, containing one or more additivestogether, with a certain amount of base oil diluents. Accordingly, theweight amounts in the table below, as well as other amounts mentionedherein, are directed to the amount of active ingredient (that is thenon-diluent portion of the ingredient). The weight percent (wt. %)indicated below is based on the total weight of the lubricating oilcomposition.

TABLE 1 Typical Amounts of Other Lubricating Oil Components ApproximateApproximate Compound Wt. % (Useful) Wt. % (Preferred) Dispersant  0.1-200.1-8 Detergent  0.1-20 0.1-8 Friction Modifier 0.01-5   0.01-1.5Antioxidant 0.1-5   0.1-1.5 Pour Point Depressant (PPD) 0.0-5  0.01-1.5Anti-foam Agent 0.001-3   0.001-0.15 Viscosity Modifier (solid 0.1-20.1-1 polymer basis) Antiwear 0.2-3 0.5-1 Inhibitor and Antirust 0.01-5  0.01-1.5

The foregoing additives are all commercially available materials. Theseadditives may be added independently but are usually precombined inpackages which can be obtained from suppliers of lubricant oiladditives. Additive packages with a variety of ingredients, proportionsand characteristics are available and selection of the appropriatepackage will take the requisite use of the ultimate composition intoaccount.

The following non-limiting examples are provided to illustrate thedisclosure.

EXAMPLES

The lubricating oil base stocks used herein were a liquid crystal baseoil (i.e., hexakis(octylthio)benzene) (referred to as “liquid crystal D1” herein), PAO base oils, and non-liquid crystalline base oilsincluding aromatics.

A reciprocating cylinder-on-disc (RCD) Schwingung (oscillating), Reibung(friction), Verschleiž (wear) test machine (SRV) was used to evaluatefriction coefficient of the base oils. The testing was conducted inaccordance with ASTM D5707. The SVR continuously records the frictioncoefficient as a function of time. The temperature was controlled byheating up the test assembly. Specimen materials, geometry, and typicaltest parameters used for the tests are given in Table 2 below. In theexperimental arrangement, the cylinder is shifted by about 5° to thesliding direction. All samples were degreased and cleaned with ethanoland acetone and dried before each test. Lubricants (approximately 0.025mL were applied on the cylinder before starting the friction test. Dueto the constant applied load and growing contact surface area (caused bywear), the contact pressure decreases throughout the test from initiallyabout 130 MPa to about 10 MPa after several hours in case of the typical50 newton load.

TABLE 2 Parameters Value Temperature 30° C. to 100° C. Load 5N to 100NFrequency 50 Hz Stroke 1 mm Duration 8 hours to >20 hours HertzianContact Line Contact Ambient Temperature 25° C. to 30° C. RelativeHumidity 20% to 30%

Liquid crystal D1 lowers the friction coefficient observed between acylinder and disk pair in the line contact SRV test after a run-inperiod dependent upon the temperature and pressure applied. After thefriction is reduced, it is maintained (see FIG. 1). Noise in thefriction curve is observed to decrease over time, attributable toreduction in wear-inducing events such as particle generation andstick-slip. Low viscosity Polyalphaolefins tested do not show similarfriction drop over time, and friction data remains noisy indicatingcontinued wear events or inability to level rough surfaces.

Furthermore as many as 20 other non-liquid crystalline experimentalaromatics and sulfur-containing molecules did not reach the ultralowfriction levels achieved by liquid crystal D1, and most fluids testedshowed erratic friction curves attributable to stick-slip/adhesive wear.

Evaluation of the post-test used disks from experiments in FIG. 1, usinginterferometry images shown in FIG. 3 (image “a” for PAO3.6 and image“b” for Liquid crystal D1), show PAO caused the disk to increase inroughness, and surface building is evident of an adhesive wearmechanism, while liquid crystal D1 caused pairing of disk to cylinderand also a reduced roughness, no signs of adhesive wear, and a surfacebrushing pattern.

In another experiment, after wear and ultralow friction has occurred andstabilized, without unloading the contact was flushed with solvent,dried to remove the liquid crystal D1, and subsequently flooded withpolyalphaolefin (PAO 8), of similar viscosity to liquid crystal Dl. Itis shown in FIG. 2 that after fluid exchange, friction levels on startup briefly spiked then returned to the ultralow values. The persistenceof ultralow friction even after flooding the contact with a simple fluidwas surprising.

As shown in the Examples, a principal advantage of this disclosure isthat ultra-low friction values are achievable using liquid crystal D1,while not achievable using a host of other aromatic fluids, esters, orparaffins. The smoothness of the conformed surface generated in thetests is in stark contrast to the roughness of the surface when run withsimple polyalphaolefins. Furthermore, the maintenance of ultralowfriction once achieved, even after flushing with simple fluid, shows thefluid may be able to be used in the machining of parts or as a pre-runfluid to achieve low friction in applications.

Further it has been surprisingly found that these compounds behavedifferently than most materials, especially PAO, with respect tofriction coefficient as it changes with load. Most materials exhibit noor little change in friction coefficient with respect to load or time.The inventive materials change in a surprising way with both load andtemperature as shown in FIGS. 2, 5, 6 and 10. While most lubricants donot change with respect to load, these materials show a decrease infriction coefficient at higher loads.

Surprisingly, these material exhibit a well-defined relationship betweenfriction coefficient and load such that Friction Coefficient (FC) can bedefined by a general formula: FC=Y[Load(N)]^(X), where Y an X areconstant integers.

More surprisingly, these material exhibit a well-defined relationshipbetween friction coefficient and load such that Friction Coefficient(FC) can be defined by a general formula: FC=Y[Load(N)]^(X), where Y isa constant integer of less than 1 and X value is less than zero.

Even more surprisingly, these material exhibit a well-definedrelationship between friction coefficient and load such that FrictionCoefficient (FC) can be defined by a general formula:FC=0.428[Load(N)]^(−0.84).

Further it has been surprisingly found that these compounds behavedifferently than most materials, especially PAO, with respect tofriction coefficient as it changes with temperature and load. Therelationship is seen in FIGS. 2 and 5. The dependence of temperature andsquare of the load is unexpected, especially since the higher the loadand the lower the temperature gives lower friction coefficients. TheFriction Coefficient (CF) can be defined by the general formula:FC=W[Temperature(C)/Load²(N)]Z where W and Z are both constant integers.

More surprisingly, these material exhibit a well-defined relationshipbetween friction coefficient and temperature load such that FrictionCoefficient (FC) can be defined by a general formula:FC=W[Temperature(C)/Load²(N)]z, where W and Z are both constant integersof less than 1 and greater than zero value.

Even more surprisingly, these material exhibit a well-definedrelationship between friction coefficient and load such that FrictionCoefficient (FC) can be defined by a general formula:FC=0.0769[Temperature(C)/Load2(N)]^(0.3927)

PCT and EP Clauses:

1. A lubricating oil base stock comprising one or more liquid crystals,wherein the one or more liquid crystals are represented by the formula:

A-(R1)_(n)

wherein A is a mono-ring or a multi-ring aromatic group, R1 is the sameor different and is a substituted or unsubstituted, hydrocarbon group,alkoxy, or alkylthio having from 2 to 24 carbon atoms, and n is a valuefrom 1 to 12; and wherein the lubricating oil base stock has a kinematicviscosity of 2 cSt to 200 cSt at 40° C., as determined according to ASTMD445, and a kinematic viscosity of 1 cSt to 25 cSt at 100° C., asdetermined according to ASTM D445.

2. The lubricating oil base stock of clause 1 wherein, in frictioncoefficient measurements of the lubricating oil base stock by areciprocating cylinder-on-disc (RCD) Schwingung (oscillating), Reibung(friction), Verschleiž (wear) test machine (SRV) in accordance with ASTMD5707, the friction coefficient is less than 0.25.

3. The lubricating oil base stock of clause 1 wherein, in frictioncoefficient measurements of the lubricating oil base stock by areciprocating cylinder-on-disc (RCD) Schwingung (oscillating), Reibung(friction), Verschleiž (wear) test machine (SRV) in accordance with ASTMD5707, the friction coefficient is less than 0.20.

4. The lubricating oil base stock of clause 1 wherein, in frictioncoefficient measurements of the lubricating oil base stock by areciprocating cylinder-on-disc (RCD) Schwingung (oscillating), Reibung(friction) Verschleiž (wear) test machine (SRV) in accordance with ASTMD5707, the friction coefficient is less than 0.10.

5. The lubricating oil base stock of clause 1 wherein the FrictionCoefficient (FC) can be defined by a general formula:FC=W[Temperature(C)/Load²(N)]^(z), where W and Z are both independentlyconstant integers of less than 1 and greater than zero value.

6. The lubricating oil base stock of clause 1 wherein the FrictionCoefficient (FC) can be defined by a general formula:FC=0.08[Temperature(C)/Load²(N)]^(0.4).

7. The lubricating oil base stock of clause 1 wherein the FrictionCoefficient (FC) can be defined by a general formula: FC=Y[Load(N)]^(X),where Y is a constant integer of less than 1 and X value is less thanzero.

8. The lubricating oil base stock of clause 1 wherein the FrictionCoefficient (FC) can be defined by a general formula:FC=0.4[Load(N)]^(−0.8).

9. The lubricating oil base stock of clauses 1-8 wherein the one or moreliquid crystals are represented by the formula:

10. The lubricating oil base stock of clauses 1-8 wherein the one ormore liquid crystals comprise hexakis(octylthio)benzene.

11. The lubricating oil base stock of clauses 1-10 which is a machiningor pre-run fluid for smoothing and conforming mated metal surfaces.

12. A method for improving friction and wear control, while maintainingor improving energy efficiency, in an engine or other mechanicalcomponent lubricated with a lubricating oil, by using as the lubricatingoil a formulated oil, said formulated oil having a compositioncomprising at least one lubricating oil base stock; wherein the at leastone lubricating oil base stock comprises one or more liquid crystals,wherein the one or more liquid crystals are represented by the formula:

A-(R1)_(n)

wherein A is a mono-ring or a multi-ring aromatic group, R1 is the sameor different and is a substituted or unsubstituted, hydrocarbon, alkoxy,or alkylthio group having from 2 to 24 carbon atoms, and n is a valuefrom 1 to 12; and wherein the lubricating oil base stock has a kinematicviscosity of 2 cSt to 200 cSt at 40° C., as determined according to ASTMD445, and a kinematic viscosity of 1 cSt to 25 cSt at 100° C., asdetermined according to ASTM D445; and wherein friction and wear controlare improved and energy efficiency is maintained or improved as comparedto friction control, wear control and energy efficiency achieved using alubricating oil containing a lubricating oil base stock other than thelubricating oil base stock comprising one or more liquid crystals.

13. The method of clause 12 wherein, in friction coefficientmeasurements of the lubricating oil base stock by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than 0.25.

14. The method of clause 12 wherein, in friction coefficientmeasurements of the lubricating oil base stock by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than 0.20.

15. The method of clause 12 wherein, in friction coefficientmeasurements of the lubricating oil base stock by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than 0.10.

16. The method of clauses 12-15 wherein the one or more liquid crystalsare represented by the formula:

17. The method of clauses 12-15 wherein the one or more liquid crystalscomprise hexakis(octylthio)benzene.

18. The method of clauses 12-17 wherein the lubricating oil is amachining or pre-run fluid for smoothing and conforming mated metalsurfaces.

19. A method for improving and maintaining friction and wear control inan engine or other mechanical component lubricated with a lubricatingoil, said method comprising:

-   -   (i) providing an engine or other mechanical component having        mated metal surfaces;    -   (ii) conducting a run-in by contacting the mated metal surfaces        with a first lubricating oil having a composition comprising at        least one lubricating oil base stock; wherein the at least one        lubricating oil base stock comprises one or more liquid        crystals, wherein the one or more liquid crystals are        represented by the formula:

A—(R1)_(n)

wherein A is a mono-ring or a multi-ring aromatic group, R1 is the sameor different and is a substituted or unsubstituted, hydrocarbon, alkoxy,or alkylthio group having from 2 to 24 carbon atoms, and n is a valuefrom 1 to 12; and wherein the lubricating oil base stock has a kinematicviscosity of 2 cSt to 200 cSt at 40° C., as determined according to ASTMD445, and a kinematic viscosity of 1 cSt to 25 cSt at 100° C., asdetermined according to ASTM D445; wherein friction and wear control areimproved as compared to friction control and wear control achieved usinga lubricating oil containing a lubricating oil base stock other than thelubricating oil base stock comprising one or more liquid crystals;

-   -   (iii) removing the first lubricating oil from the engine or        other mechanical component after the run-in; and    -   (iv) contacting the mated metal surfaces with a second        lubricating oil containing a lubricating oil base stock other        than the lubricating oil base stock comprising one or more        liquid crystals; wherein the improved friction control and wear        control from conducting the run-in are maintained.

All patents and patent applications, test procedures (such as ASTMmethods, UL methods, and the like), and other documents cited herein arefully incorporated by reference to the extent such disclosure is notinconsistent with this disclosure and for all jurisdictions in whichsuch incorporation is permitted.

When numerical lower limits and numerical upper limits are listedherein, ranges from any lower limit to any upper limit are contemplated.While the illustrative embodiments of the disclosure have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by thoseskilled in the art without departing from the spirit and scope of thedisclosure. Accordingly, it is not intended that the scope of the claimsappended hereto be limited to the examples and descriptions set forthherein but rather that the claims be construed as encompassing all thefeatures of patentable novelty which reside in the present disclosure,including all features which would be treated as equivalents thereof bythose skilled in the art to which the disclosure pertains.

The present disclosure has been described above with reference tonumerous embodiments and specific examples. Many variations will suggestthemselves to those skilled in this art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims.

1. A lubricating oil base stock comprising one or more liquid crystals,wherein the one or more liquid crystals are represented by the formula:A—(R1)_(n) wherein A is a mono-ring or a multi-ring aromatic group, R1is the same or different and is a substituted or unsubstituted,hydrocarbon group, alkoxy, or alkylthio having from about 2 to about 24carbon atoms, and n is a value from about 1 to about 12; and wherein thelubricating oil base stock has a kinematic viscosity of about 2 cSt toabout 200 cSt at 40° C., as determined according to ASTM D445, and akinematic viscosity of about 1 cSt to about 25 cSt at 100° C., asdetermined according to ASTM D445.
 2. The lubricating oil base stock ofclaim 1 wherein, in friction coefficient measurements of the lubricatingoil base stock by a reciprocating cylinder-on-disc (RCD) Schwingung(oscillating), Reibung (friction) test machine, Verschleiž (wear) (SRV)in accordance with ASTM D5707, the friction coefficient is less thanabout 0.25.
 3. The lubricating oil base stock of claim 1 wherein, infriction coefficient measurements of the lubricating oil base stock by areciprocating cylinder-on-disc (RCD) Schwingung (oscillating), Reibung(friction), Verschleiž (wear) test machine (SRV) in accordance with ASTMD5707, the friction coefficient is less than about 0.20.
 4. Thelubricating oil base stock of claim 1 wherein, in friction coefficientmeasurements of the lubricating oil base stock by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than about 0.10.
 5. The lubricating oilbase stock of claim 1 wherein the Friction Coefficient (FC) can bedefined by a general formula: FC=W[Temperature(C)/Load²(N)]^(z), where Wand Z are both independently constant integers of less than 1 andgreater than zero value.
 6. The lubricating oil base stock of claim 1wherein the Friction Coefficient (FC) can be defined by a generalformula: FC=0.08[Temperature(C)/Load2(N)]^(0.4).
 7. The lubricating oilbase stock of claim 1 wherein the Friction Coefficient (FC) can bedefined by a general formula: FC=Y[Load(N)]^(X), where Y is a constantinteger of less than 1 and X value is less than zero.
 8. The lubricatingoil base stock of claim 1 wherein the Friction Coefficient (FC) can bedefined by a general formula: FC=0.4[Load(N)]^(−0.8).
 9. The lubricatingoil base stock of claim 1 wherein the one or more liquid crystals arerepresented by the formula:


10. The lubricating oil base stock of claim 1 wherein the one or moreliquid crystals comprise hexakis(octylthio)benzene.
 11. The lubricatingoil base stock of claim 1 further comprising one or more of an antiwearadditive, viscosity modifier, antioxidant, detergent, dispersant, pourpoint depressant, corrosion inhibitor, metal deactivator, sealcompatibility additive, anti-foam agent, inhibitor, or anti-rustadditive.
 12. The lubricating oil base stock of claim 1 which is amachining or pre-run fluid for smoothing and conforming mated metalsurfaces.
 13. A method for improving friction and wear control, whilemaintaining or improving energy efficiency, in an engine or othermechanical component lubricated with a lubricating oil, by using as thelubricating oil a formulated oil, said formulated oil having acomposition comprising at least one lubricating oil base stock; whereinthe at least one lubricating oil base stock comprises one or more liquidcrystals, wherein the one or more liquid crystals are represented by theformula:A—(R1)_(n) wherein A is a mono-ring or a multi-ring aromatic group, R1is the same or different and is a substituted or unsubstituted,hydrocarbon, alkoxy, or alkylthio group having from about 2 to about 24carbon atoms, and n is a value from about 1 to about 12; and wherein thelubricating oil base stock has a kinematic viscosity of about 2 cSt toabout 200 cSt at 40° C., as determined according to ASTM D445, and akinematic viscosity of about 1 cSt to about 25 cSt at 100° C., asdetermined according to ASTM D445; and wherein friction and wear controlare improved and energy efficiency is maintained or improved as comparedto friction control, wear control and energy efficiency achieved using alubricating oil containing a lubricating oil base stock other than thelubricating oil base stock comprising one or more liquid crystals. 14.The method of claim 13 wherein, in friction coefficient measurements ofthe lubricating oil base stock by a reciprocating cylinder-on-disc (RCD)Schwingung (oscillating), Reibung (friction), Verschleiž (wear) testmachine (SRV) in accordance with ASTM D5707, the friction coefficient isless than about 0.25.
 15. The method of claim 13 wherein, in frictioncoefficient measurements of the lubricating oil base stock by areciprocating cylinder-on-disc (RCD) Schwingung (oscillating), Reibung(friction), Verschleiž (wear) test machine (SRV) in accordance with ASTMD5707, the friction coefficient is less than about 0.20.
 16. The methodof claim 13 wherein, in friction coefficient measurements of thelubricating oil base stock by a reciprocating cylinder-on-disc (RCD)Schwingung (oscillating), Reibung (friction), Verschleiž (wear) testmachine (SRV) in accordance with ASTM D5707, the friction coefficient isless than about 0.10.
 17. The method of claim 13 wherein the FrictionCoefficient (FC) can be defined by a general formula:FC=W[Temperature(C)/Load²(N)]^(z), where W and Z are both independentlyconstant integers of less than 1 and greater than zero value.
 18. Themethod of claim 13 wherein the Friction Coefficient (FC) can be definedby a general formula: FC=0.08[Temperature(C)/Load²(N)]^(0.4).
 19. Themethod of claim 13 wherein the Friction Coefficient (FC) can be definedby a general formula: FC=Y[Load(N)]^(X), where Y is a constant integerof less than 1 and X value is less than zero.
 20. The method of claim 13wherein the Friction Coefficient (FC) can be defined by a generalformula: FC=0.4[Load(N)]^(−0.8).
 21. The method of claim 13 wherein theone or more liquid crystals are represented by the formula:


22. The method of claim 13 wherein the one or more liquid crystalscomprise hexakis(octylthio)benzene.
 23. The method of claim 13 whereinthe lubricating oil further comprises one or more of an antiwearadditive, viscosity modifier, antioxidant, detergent, dispersant, pourpoint depressant, corrosion inhibitor, metal deactivator, sealcompatibility additive, anti-foam agent, inhibitor, and anti-rustadditive.
 24. The method of claim 13 wherein the lubricating oil is amachining or pre-run fluid for smoothing and conforming mated metalsurfaces.
 25. A method for improving and maintaining friction and wearcontrol in an engine or other mechanical component lubricated with alubricating oil, said method comprising: (i) providing an engine orother mechanical component having mated metal surfaces; (ii) conductinga run-in by contacting the mated metal surfaces with a first lubricatingoil having a composition comprising at least one lubricating oil basestock; wherein the at least one lubricating oil base stock comprises oneor more liquid crystals, wherein the one or more liquid crystals arerepresented by the formula:A—(R1)_(n) wherein A is a mono-ring or a multi-ring aromatic group, R1is the same or different and is a substituted or unsubstituted,hydrocarbon group, alkoxy, or alkylthio having from about 2 to about 24carbon atoms, and n is a value from about 1 to about 12; and wherein thelubricating oil base stock has a kinematic viscosity of about 2 cSt toabout 200 cSt at 40° C., as determined according to ASTM D445, and akinematic viscosity of about 1 cSt to about 25 cSt at 100° C., asdetermined according to ASTM D445; wherein friction and wear control areimproved as compared to friction control and wear control achieved usinga lubricating oil containing a lubricating oil base stock other than thelubricating oil base stock comprising one or more liquid crystals; (iii)removing the first lubricating oil from the engine or other mechanicalcomponent after the run-in; and (iv) contacting the mated metal surfaceswith a second lubricating oil containing a lubricating oil base stockother than the lubricating oil base stock comprising one or more liquidcrystals; wherein the improved friction control and wear control fromconducting the run-in are maintained.
 26. The method of claim 25wherein, in friction coefficient measurements of the lubricating oilbase stock of the first lubricating oil by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than about 0.25.
 27. The method of claim 25wherein, in friction coefficient measurements of the lubricating oilbase stock of the first lubricating oil by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than about 0.20.
 28. The method of claim 25wherein, in friction coefficient measurements of the lubricating oilbase stock of the first lubricating oil by a reciprocatingcylinder-on-disc (RCD) Schwingung (oscillating), Reibung (friction),Verschleiž (wear) test machine (SRV) in accordance with ASTM D5707, thefriction coefficient is less than about 0.10.
 29. The method of claim 25wherein the Friction Coefficient (FC) can be defined by a generalformula: FC=W[Temperature(C)/Load²(N)]^(z), where W and Z are bothindependently constant integers of less than 1 and greater than zerovalue.
 30. The method of claim 25 wherein the Friction Coefficient (FC)can be defined by a general formula:FC=0.08[Temperature(C)/Load²(N)]^(0.4).
 31. The method of claim 25wherein the Friction Coefficient (FC) can be defined by a generalformula: FC=Y[Load(N)]^(X), where Y is a constant integer of less than 1and X value is less than zero.
 32. The method of claim 25 wherein theFriction Coefficient (FC) can be defined by a general formula:FC=0.4[Load(N)]^(0.8).
 33. The method of claim 25 wherein the one ormore liquid crystals are represented by the formula:


34. The method of claim 25 wherein the one or more liquid crystalscomprise hexakis(octylthio)benzene.
 35. The method of claim 25 whereinthe first and second lubricating oils further comprise one or more of anantiwear additive, viscosity modifier, antioxidant, detergent,dispersant, pour point depressant, corrosion inhibitor, metaldeactivator, seal compatibility additive, anti-foam agent, inhibitor oranti-rust additive.